compose

All matrices of a given column within parts must have the same number of columns.
All matrices of a given row within parts must have the same number of rows.
Otherwise an IllegalArgumentException is thrown.
Note that nulls within parts[row,col] are an exception to this rule: they are ignored.
Cells are copied.
Example:

decompose

Splits a block matrix into its constituent blocks; Copies blocks of a matrix into the given parts.
The inverse to method compose(ObjectMatrix2D[][]).

All matrices of a given column within parts must have the same number of columns.
All matrices of a given row within parts must have the same number of rows.
Otherwise an IllegalArgumentException is thrown.
Note that nulls within parts[row,col] are an exception to this rule: they are ignored.
Cells are copied.
Example: